1. Field of the invention:
The present invention relates to a support for an alkali.removable label used for a beer bottle etc. More particularly, this invention is concerned with a support for a label which is used for providing an alkali removable label having excellent water resistance and excellent bottle washing suitability.
2. Description of the Prior Art:
A lacquer of a nitrocellulose resin, an acrylic resin, a urethane resin, or a vinyl chloride/vinyl acetate copolymer resin has been used as an anchor layer on a support for the purpose of preparing a highly glossy and water-resistant paper label for a beer bottle etc. or preparing a metallized label. However, when the above-described resin is used, the resultant label is poor in the bottle washing suitability, which renders the label unsuitable for use as an alkali-removable label for a returnable bottle. In bottle washing, a returned bottle is immersed in a 1 to 4 % aqueous sodium hydroxide solution having a high temperature to remove the label from the bottle. When the label is easily washed off by the above-described means, such a label is hereinafter defined as having good suitability for bottle washing. The suitability is evaluated based on the time taken from immersion of the returned bottle to removing of the label. For the purpose of improving the suitability for bottle washing, in Japanese Patent Application Laid-Open No. 222873/1984, a proposal has been made to use as the anchor layer a resin comprising a maleic acid-containing aminoalkyd resin; a maleic resin; a resin comprising a nitrocellulose resin and a fatty acid ester added thereto; or an acrylic resin comprising a copolymer of a methacrylic ester with an acrylic ester and acrylic acid. Use of the above-described anchor layer contributed to an improvement in the bottle washing suitability but brought about drawbacks such as insufficient gloss, occurrence of many pinholes which renders the support unsuitable as a support for a label, large curling which hinders subsequent steps such as printing and application to a bottle, and occurrence of cracking on a metallized surface when a metallized label is formed and then immersed into water.
In Japanese Patent Application Laid-Open Nos. 163294/1980 and 185575/1986, a proposal has been made of a method which comprises applying an electron beam-curable composition on a support and irradiating the resultant coating with an electron beam, thereby forming an anchor layer for aluminum metallization. The support for a label thus formed has the advantages of as high gloss, water resistance and an improvement in adhesion to aluminum but is poor in suitability for bottle washing, which renders the support unsuitable for use in an alkali-removable label. For the purpose of improving the suitability for bottle washing, in Japanese Patent Application Laid-Open No. 68186/1981, a proposal has been made to incorporate into an electron beam. curable composition a compound having a combination of a polymerizable double bond with a tertiary amino group and a hydroxyl group and/or an ether bond, or a quaternary ammonium salt. However, this method has the problems that no intended gloss can be obtained, water resistance is insufficient and cracking occurs on a metallized surface when a metallized label is formed and then immersed into water.
Use of the above-described anchor layers contributed to an improvement in bottle washing suitability, but brought about drawbacks such as insufficient gloss, occurrence of many pinholes which rendered the support unsuitable as a support for a label, large curling which hindered subsequent steps such as metallization, printing and application to a bottle, and occurrence of cracking when a label is formed with the support and then immersed into water.
A first object of the present invention therefore is to provide an alkali-removable label support and a label made therefrom wherein an anchor layer is provided on base layer for the purpose of improving the labels suitability for bottle washing while, at the same time, providing a support for a label that has sufficient gloss, less number of pinholes and less degree of curling, is suitable for use in subsequent steps such as metallization, printing or application to a bottle and has water resistance sufficient to prevent occurrence of cracking when immersed in water.
A second object of the present invention is to provide a support for an alkali-removable label and a label made therefrom wherein an intermediate layer is used to prevent the resin composition applied to base layer for the purpose of forming the above-described anchor layer from penetrating into the base layer is provided.
A third object of the present invention is to provide a support for an alkali-removable label and a label made therefrom which, when immersed in an alkaline solution to remove the label from a bottle, causes the anchor layer to rapidly swell without dissolution and be washed off in film form, thus enabling the label and the anchor layer to be easily recovered and causing no deterioration of the alkali solution.